Headlight reflector



March 1927' J. F. RAYNOLDS HEADLIGHT REFLECTOR 4 Sheets-Sheet 1 FiledApril 27. 192.5

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irron lvk Y's 17v YEN Ton Patented Mar. 22, 1927.

, UNITED sra'ras PATENT OFFICE.

JOHN F. RAYNOLDS, or MINNEAPOLIS, MINNESOTA, ASSIGTNOR TO THErARAFL-Eo'r'on COMPANY, OF MINNEAPOLIS, MINNESOTA, A CORPORATION OFDELAWARE.

HEADLIGHT REFLECTOR.

Application filed April 27, 1925.

This invention has for its main obj ect the projection of a beam oflight for use 1n motor vehicle head lamps and the like, having a. moredesirable shape, and with better distribution of candle-power or lightintensities than is aiiiorded' by the various devices now in use.

The invention consists generally in the construction and arrangement ofparts forming a reflector as hereinafter described and particularlypointed out in the claims.

In the accompany'ng drawings forming part of this specification,

Figure 1 illustrates a front elevation of a reflector having its surfacedivided into strips by means of circular arcs; lines I-1 etc. indicatingthe planes in which the light is spread. from various points on a singlestrip; pp

Figure 2, is a horizontal. sectional view on the line 2,-'-2 of Figure 1showing a reflector of preferred form, comprising a plurality of flatstrips arranged to produce the desired spread of the reflected lightrays;

Figure 3 is av diagrammatic view illustrating a cross section of a lightbeam from two headlamps arranged as on a motor vehicle', to show theparticular form of beam structure which, it is desired to produce torilluminating the roadway ahead oi" said vehicle;

Figure t illustrates a front elevation of a single strip formec'tfrom acircular parabolic reflecting surface as shown in Figure 2, b h being atransverse element lying in plane Pat its intersection with strip S;

Figure 5 illustrates a side elevation of't he strip shown in Figure 4,showing its curvature in a vertical plane parallel to the principal axisof the reflector.

Figure 6 illustrates an enlarged cross sectional view in plane P (Figure4;), showing various curvatures into which the transverse element of thestrip may be formed to give a, desired amountof spread or divergenes tothe reflected'rays Figures 7 and8 are modiflcationsshowing reflectorshaving differently designed curvatures of reflecting strips to producevarying amounts of divergence to the rays striking said strips;

Figure 9illustrates a front elevation'o'f a modified form of reflectorshowin'gthestrips arranged in non-circular continuous curves,

the whole axes Serial No. 26,105.

identical in curvature and symmetrically arranged with respect to thevertical meridian V-V; and

Figure 10 illustrates a method of laying out the surface of a reflector(or die) into strips, using circular arcs.

It is well recognized by illuminating engineers that thelight'beamprojected from the headlamps of motor vehicles should have apattern in cross section similar to that shown in Figure 3' and that thedistribution of light intensities within such a beam should besubstantially as shown by the lines of equal intensity in Figure 3.

The figures merely indicate the comparative candle powers in a suitablebeam projected from two lamps, when correctly adjusted as on a motorvehicle and "readings made at 100 feet. This beam resembles onehalf ofan ellipse, divided on its major axis, preferably having a ratio ofabout 1.8 to 1. I I

The commonest form of reflector used in motor vehicle headlamps is acircular paralbolic reflector of about 1 7 focal length (paraboloid ofrevolution)- There are also a number of patented reflectors having anunbroken reflecting surface but which are non-circular in sectionstransverse to the principal axis, being so designed according to acertain plan or theory, which causes the light rays to be projected inlines which de viate from parallelism by an. amount measurably greaterthan in the case ofthe abovementioned circular parabolic reflector-thesource of light being considered the same and adjusted for leastdivergence of the rays.

The improvement disclosedherewith' is distinctly applicable to bothclasses or rex I rays m-one plane or in several'planes. They must bespread in continuously changing planes depending upon the point on thereflectin surface which is under consideration.

By constructing the reflector with a plurality of strips 11, (as shownin Figures 1 and 2) whose edges are continuous curved lines if projectedon the plane of the reflectors mouth perpendicular to the principalaxis; and by the use of suitably curved cross sections or transverseelements, for symmetrically located strips, the most desirable andetlicient distribution of light may be secured in a beam of correctcross-section or pattern. Instead of spreading the rays horizontally (inone plane), thus producing a band of light with highest intensity nearits horizontal center line; the distance and direction of travel of thevarious rays are considered, and the reflecting surface made to directthe proper amount of light to each portion of the lighted field which isassumed to be a level, slightly crowned highway.

My invention consists of a broken, divided or configurated reflectingsurface, originally either paraboloidal in shape or modified as abovementioned, said surface being divided into two series of strips, whichare symmetrically arranged about the vertical meridian VV of thereflector. The bounding edges of these strips are continuously curvedlines or circular arcs when projected on a plane perpendicular to themain axis of the reflector (plane of reflector mouth opening) havingtheir convex sides toward the vertical meridian of the reflector. Brokenlines 11, 2-2, etc, in Figure 1, show the planes in which light isspread from points on various transverse elements of a single strip. Thesurface of the strips at such transverse elements is made to assume acurvature less marked than that of the original smooth surface or it maybe made flat or plane, or may have a curvature opposite to that of theoriginal reflector surface, i. e. convex with relation to the mainreflector axis (Figure 8). Furthermore the radius of curvature of astrip at any such transverse element may be greater near one edge thanthe other so as to produce greater deviation of the rays in onedirection in the spreading plane than in the other. With this method orcombination of methods practically any desired alteration may beeffected in a beam from a reflector as described above, and thedistribution of light within the projected beam may be arranged to bestmeet the requirements of State laws and actual conditions of service. Nodiffusing or refracting lens is necessary, only a piece of clear sheetglass as a cover in the lamp door is required. Loss of light byabsorption and diffusion is diminished.

The light is concentrated to a proper ex tent, in the upper centralportion of the beam (Figure 3), thus illuminating more distant points onthe roadway and producing less apparent change in illumination to theoperators eye as it is directed along the lighted path.

Referringto Figure 4, the transverse element bb originally had a smallerradius of curvature as a part of the unbroken circular parabolic surfacebefore this surface was divided into strips and reformed, as shown ata-a, Figure 6. Line TT' is tangent to the curved edge of the strip atZ). Now in Figure 5, the inclination of plane P to the horizontal isfixed by its construction )erpendicular to the tangent TT. Plane itcontains the transverse element 72-1), also its radius of curvaturewhich is centered at in Figure 6. This figure shows an enlarged view inplane P of the transverse element b-b and also shows the originalcurvature of this element at a-a, with radius centered at 0, togetherwith c--c a straight line or flat transverse element with radius ofcurvature infinite, andd-d' having its center of curvature on theopposite side of the strip.

The preferred embodiment consists of a reflecting surface divided intostrips whose edges are concentric circular arcs when projected on theplane of the reflector mouth opening. Figure 10 illustrates how thesearcs may be constructed. In this case a single base line perpendicularto the vertical meridian plane of the reflector is used. The centers ofthe two series of ares are located on this line equidistant from themeridian plane, The radius arm 12 is adapted to slide vertically on theupright post or rod 13, so as to preserve the same radius throughout agiven are.

Where arcs of'equal radius are used as illustrated in Figure 9, thescribing point on arm 12 retains the same radius or distance from post13, while post 13 is moved away from or toward the vertical meridianplane of the reflector die, in order to describe circular arcs of equalradii on the surface of the die.

I claim as my invention:

1. A concave reflector having its surface divided into two series ofstrips or zones; each strip being formed so that its mean radius ofcurvature, in the plane containing a transverse element of said strip,is greater than the means radius of curvature of the same section of theoriginal surface; said strips or zones arranged symmetrically withrespect to the vertical meridian of said reflector and having theiredges in curved lines on the reflector surface, the projections of saidlines on a plane perpendicular to the main axis of said reflectorforming two series of concentric circular arcs having their centers onopposite sides of the projected vertical meridian, equidistant from itand below the horizontal axial plane, said arcs lying between theprojected vertical meridian and their respective centers.

2. A concave reflector having its surface divided into two series ofstrips or zones; each strip being formed so that its mean radius ofcurvature, in the plane containing a transverse element of said strip,is greater than the mean radius of curvature of the same section of theoriginal surface; said strips or zones arranged symmetrically withrespect to the vertical meridian of said reflector and having theiredges in curved lines on the reflector surface the projections of saidlines on a plane perpendicular to the main axis of said reflectorforming two series of circular arcs of equal radii and having theircenters on opposite sides of the projected vertical merdian and belowthe horizontal axial plane of said reflector, said arcs lying betweenthe projected vertical meridian and their respective centers.

In witness whereof, I have hereunto set,

my hand this 14th day of April, 1925.

JOHN F. RAYNOLDS.

